Agricultural harvesters such as combine and forage harvesters usually have one or two large rotors for threshing and separating the harvested crop material. In axial flow harvester, the rotors are arranged along the longitudinal axis of the harvester. In such axial flow harvesters, the crop material is subjected to a much longer threshing and separation cycle than in conventional harvesters and therefore, the efficiency of the axial flow harvesters is greater. A high separation degree is reached and a reduction of the grain loss is obtained.
The rotors of harvesters are provided with an infeed section, also called charging or inlet section, for receiving harvested crop material that was harvested from the field, a threshing section for threshing and separating grain out of the threshed mixture, a separating section for freeing remaining grain trapped in the threshed crop material received from the threshing section and an outlet section or discharge section for discharging the discardable part of the crop material.
It is known to a man skilled in the art to provide a housing for receiving a threshing and separating rotor with, secured to the inside of the housing, numerous helical guide vanes, also called bars or discharge flights, that are arranged underneath the cover element of the rotor housing. It is known that these vanes have a big impact on the transportation of the harvested crop material in the rotors in that way that the residence time of the crop material in the separating section is a function of the inclination of the vanes, that is, the angle of inclination, also called the pitch angle, between the vanes and the radius of the rotor.
Varying crop conditions within a field such as population and yield, moisture content, combined with atmospheric conditions such as humidity do have a big impact on the harvesting process. Operating parameters or settings are made during the harvesting process to accommodate with the conditions to optimize the processes such as, but not restricted to, threshing rotor speed and concave gap (adaptable distance between a perforated concave region of the threshing casing and the rotating rotor contained therein). Various inputs are used by the operator to optimize the settings in the given crop type and condition such as grain loss, grain sample, power consumption and the like.
The position of the vanes controlling the transportation of the harvested crop material through the axial rotor(s) is a very good way to anticipate on these harvesting conditions to search for the best fuel efficiency, reduced losses of wheat, beans or grains, straw quality, etc, also taking into care other factors such as grain cracking and other damage to the wheat, beans, grain, etc. and losses thereof. It is therefore known to make the vanes adjustable in order to vary the rate of axial progression of the harvested crop material through the separator so as to control the efficiency of threshing and separating. A smaller vane pitch angle setting will reduce in the rearward speed of the flow of the crop material and will typically result in the crop material flowing in a correspondingly steeper or tighter helical path through that region of the threshing cage, and thus greater dwell time in the threshing part of the rotor for threshing and separating. A larger vane pitch angle will increase in the rearward speed of the flow of the crop material and will result in crop material flow at a less steep or looser helix and less dwell time, threshing and separating. Small grain crops such as wheat and rice do not have to remain in the separating zone as long as corn, so it is desirable when smaller grains are being threshed to have a larger pitch angle for the vanes than when threshing for example corn.
A first known possibility for adjusting these vanes is that the operator manually adjusts them. The disadvantage thereof is that the operator has to leave the cabin and wrench for about 20 minutes to change the position of the vanes. Furthermore, the space between the grain tank and the rotor is not easily accessible and therefore the vanes are only changed in case of big issues as for instance losses of power. The combine harvester consequently is not optimally used in terms of setting resulting in less efficiency and productivity.
A second possibility is a remote control for the vane adjustment which will allow adjustment “on the go”.
Already systems are known that allow vanes to be changed from the cabin but only when the rotor is standing still. This does not allow adjustment of the combine harvester on the go.
In US 2011/0320087, a system is disclosed for remote control of an adjustable threshing cage vane, including while the threshing system is operating, utilizing an actuator in connection with an at least one vane and remotely controllable for adjustably varying the position thereof within the cage for altering the path of the flow of the crop material therethrough.
In US 2010/0093413, all of the adjustable vanes are ganged together and moved together. A mechanism is provided to swing the adjustable vanes from a position corresponding to the normal helical path of the fixed vanes to a bypass position wherein crop flow through the adjustable vanes will skip one or more passes between the fixed vanes on the next pass through the fixed vanes.
A problem that arises with the adjustment of the vanes is that the vanes seal against a cylindrically formed cover and thus have a certain curvature. Consequently, in order to change in position relative to this cylindrically formed cover for quicker or slower transportation speed of the crop material throughout the rotors, the radius of the vanes needs to change. As a consequence, either the vanes or the cover has to be deformed. A first disadvantage thereof is that there is a risk that the vanes do not connect against the cylindrically formed cover, and thus gaps between the vanes and the cover occur which can become clogged because dirt can get stuck in these gaps through which it is more difficult or even impossible to move the vanes without these gaps previously being cleaned. A second disadvantage thereof is that this deformation unwillingly can significantly change the material flow characteristics for this rotor section.
Shortening the vanes in order to reduce deformation is helpful, but the effect is then less on the transportation of the crop material throughout the rotors.
In US 2010/0093413 as already cited above, in order to solve the abovementioned problem, an adjustable vane system for an axial-flow, rotary combine housing is described, wherein this housing incorporates at least one flat wall section as part of the otherwise cylindrical or oblong, curved housing cover, and adjustable vanes having flat bases that are angularly adjusted on the surface of the flat wall section. The housing therewith includes fixed vanes on a curved portion of the housing cover that have lead ends, in a direction of circumferential crop movement, substantially in registry with trailing ends of the adjustable vanes. The adjustable vanes include pivot connections near the trailing ends and swing connections near the lead ends of the adjustable vanes.
A first disadvantage thereof is that the length of straight vanes is very small and the impact on the transportation of the crop material throughout the rotors consequently is also smaller. A second disadvantage thereof is that the fixed and the adjustable vanes do not form a continuous curve anymore and form gaps between these vanes into which crop material can get clogged.
There consequently exists the need to provide a rotor housing assembly for a harvester according to the preamble of the first claim, wherein the curvature radius of the vanes does not have to be changed when the transportation speed of the crop material through the rotors has to be changed and thus the operating characteristics of the axial flow harvester are not adversely affected.